354 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



body or furnished by the body to make up the deficiency in caloric 

 intake. But the nitrogen thus lost is undoubtedly an appreciable 

 percentage of the total body-nitrogen. A subsequent discussion of 

 the energy transformations of these men shows that a very great 

 lowering of energy transformation takes place simultaneously with 

 the loss in body-weight and the loss of this excess nitrogen. Our 

 suggestion is that the nitrogen thus lost comes from the fluid bathing 

 the cells, and is in some form which stimulates them to their normal 

 level of activity. We have, therefore, loss of body-nitrogen closely 

 correlated with general loss in body-weight and with reduced intake of 

 energy. 



It is to be remembered that with these men the loss in body-weight 

 resulted in general from a deficiency in the intake of food. In certain 

 cases this deficiency of intake was undoubtedly supplemented in its 

 effect upon the body-weight4oss by excessive physical exercise. An 

 interesting problem immediately suggests itself as to what would have 

 been the influence of the nitrogen loss had the caloric intake remained 

 constant and had the body-weight loss been produced by excessive 

 physical exercise alone, a problem of far-reaching physiological im- 

 portance and possibly of considerable athletic significance. 



CORRECTION OF PRELIMINARY STATEMENTS. 



It is necessary at this time to point out an error made recently by us 

 in a preliminary report of this research before the National Academy of 

 Sciences in Washington, D. C. In this report it was stated that "the 

 nitrogen output per day at the maintenance diet of 2,300 net calories 

 was about 9 grams. A control group of 12 men, living substantially 

 the same life and eating in the same dining-room, but with unrestricted 

 diet, showed a nitrogen output of 16 to 17 grams per day."^ Three 

 serious errors appeared in this statement: 



(1) The caloric intake at the lowest weight level was not 2,300 

 calories, but 1,950 calories. 



(2) An examination of the nitrogen balance tables (tables 46 to 58) 

 shows clearly that the value of 9 grams for the nitrogen excretion at the 

 lowest level of weight maintenance (December 3 to February 3) is too 

 small, and that it should be 10.5 grams (see table 73). While one sub- 

 ject, Tom, excreted only 7.7 grams, another subject. Can, excreted 

 invariably over 11 grams (see table 35) and averaged 12.0 grams. 



(3) The statement that a control group of 12 men excreted from 16 

 to 17 grams is erroneous in that these figures represent not the nitrogen 

 excretion but the nitrogen of the food. By reference to table 32 it can 

 be seen that the nitrogen intake of a control group of 12 men ranged in 

 5 days from 17.06 to 20.80 grams, with an average of 18.46 grams. As 

 has already been stated, our information regar ding the normal excre- 



^ Benedict and Roth, Proc. Nat. Acad. Sci., 1918, 4, p. 151. 



